Physics, science 1 Investigation- Experiment to Find out the factors that effect resistance in a Wire
Scientific Basis
An electrical current can pass through a metal because the electrons in the outer shell of the wires’ atoms are allowed to flow freely throughout the wire. So when you place a Cathode (negatively charged) on one end of a wire and an Anode (positively charged) on the other and allow an electrical current to pass through, the electrons can move freely between the Anode and the Cathode
Resistance occurs when the negatively charged electrons travelling through a wire a wire, from the Cathode to the Anode, collide with the atoms of the wire.
There are several factors that affect the level of resistance produced by a wire, these are:
- Temperature; when the atoms and the wire are heated up, the atoms will vibrate because of their increase in energy. This will cause an increase in collisions because there is more chance of the atoms getting in the path of an electron and there being a collision. This increase in collisions will increase the resistance in a wire.
- Material; some metal atoms have more electrons in the outer shell so if an electrical current is passed through the wire there is more chance of an electron getting to the Anode thus decreasing resistance. Some metals are denser that others so there are more particles for the electrons to collide with thus increasing resistance, or if those atoms have a lot of electrons in their outer shell and the wire is a denser metal than another wire then there is again more chance of an electron getting to the Anode thus decreasing resistance. Some metal atoms are larger than others so there is again more chance of an electron colliding with an atom thus increasing the resistance within a wire. But for some atoms the increased size of the atom is due to the amount of shells containing electrons that the atom has, so if the atom has many shells then the positively charged nucleus of the atom will have less power of attraction over the electrons in the outer shell of the atom so less chance of electrons being pulled towards the atoms causing a collision and thus decreasing the resistance within a wire.
- Wire length; if the length of the wire increases then so will the resistance because the distance that the electrons will have to travel will be increased and there will be a greater chance of the electrons colliding with the atoms. Due to this the length increase should be proportional to the resistance increase.
- Wire Width; if the wires width is increased the resistance will decrease. This is because of the increase in the space for the electrons to travel through. Due to this increased space between the atoms there should be fewer collisions. Due to this the width increase should be inversely proportional to the resistance increase.
